/Engine/Source/Runtime/Engine/Public/HLSLTree/HLSLTreeCommon.h
Forwards to another expression, but will fallback to the 'DefaultValue' constant if the forwarded expression fails
class FExpressionDefaultValue : public [UE::HLSLTree::FExpressionForward](API\Runtime\Engine\HLSLTree\FExpressionForward)
Shader::FValue
DefaultValue